Metal graphite compacts



y 1961 M. HUMENIK, JR., E'AL 2,983,034

METAL GRAPHITE COMPACTS Filed Nov. 25.v 1959 M HUMEN/K, JR.

R. L. VAN ALSTEN INVENTOR$ A T TORNE VS METAL GRAPHITE COMPACTS NlichaelHumenik, Jr., Inkster, and Roy L. Van Alsten,

Detroit, Mich., assignors to Ford Motor Company, Dearborn, Mich., acorporation of Delaware Filed Nov. 25, 1959, Ser. No. 855,321

14 Claims. (Cl. 29182.5)

This invention relates to the powdered metal art and is morespecifically concerned with powdered metal compacts in which unusuallylarge percentages of graphite May 8, 1958, now abandoned.

Successful sintered compacts have been fabricated in which the metalcomponenthas been selected from the group of metals consisting of iron,cobalt, nickel, copper, silver and aluminum. These metals have beenemployed to bond together large amounts of either graphite or diamond.

The unusual physical properties of these metal graphite or metal diamondcompacts are'obtained-by sintering-the green compact at a temperaturesufficiently high to insure that essentially all of the metal content ofthe compact is in the liquid phase. The exact temperature of thesintering operation will depend on the melting point of the metal phase.Since all ofthe metal phase is in the liquidus state during sintering itis necessary to take certain precautions to prevent the molten metalfrom sweating out of the compact and collecting as globules on thesurface of the compact.

The figure of drawing which is a section through a globule of metalresting on a graphite stool has been presented to enable a'betterunderstanding of this invention, r

In the drawing a graphite stool has been denominated 10. A globule ofmolten metal has been denominated '11. VA tangent 12 has been drawntoglobule llwhere globule 11 intersectsgraphite stool 10. Angle A istheangle included between tangent 1 2 and the upper surface of the graphitestool as measured through the globule. The inventors have discoveredthat as long as the angle A is substantially not in excess of ninetydegrees, metal of the constitution of that in globule 11 may beincorporated in a graphite compact and sintered above the melting pointof the globule Without substantial loss of metal due to sweating. v

Mathematically angle A may be defined as follows: Cosine A is equal tothe difierence between the surface energy of the graphite and the solidliquid interfacial energy, this, difference being divided by the'surface'tensionof the liquid phase. Or, otherwise expressed,

s sl States Pate t 2,983,034 Patented May 9, 1961 where E is the surfaceenergy of the solid, B is, the

solid liquid interfacial energy and E is the surface ten- Calcium BariumStrontium Magnesium The amounts of calcium, barium, strontium, andmagnesium to be added ,to the graphite-metal compact or diamond-metalcompact are not critical. Economic factors will usually limit theaddition of these elements to the smallest amount which will produceeffective results. However, within reason larger amounts will do noharm. Because of its cheapness and ready availability, calcium in theform of calcium silicide is preferred for the pracium silicide wasapproximately 45 percent, barium, re-

mainder-silicon. The magnesium ferro silicon had a composition of about11 percent magnesium, 39 percent iron and the remainder silicon.

To illustrate this invention the following specific examples are given.

Iron graphite compacts were prepared from iron powder and graphitepowder which had been separately ground to pass a 140 mesh screen andthen ball milled together in benzene for four hours to insure propermixing. The mixture was cold pressed in a hardened steel die usingpressures of 50,000 to 100,000p0unds per square inch. The compacts weresintered in a vacuum of from 100 to 200 microns and in ambients ofhydrogen, helium and argon. The temperature of sintering was 2400 F. andthe time was sixty minutes.

The following compacts were fabricated from graphite powder and amixture consisting of 5. percent by Weight calcium silicide andpercentby weight iron powder. Any size iron powder from 60 to-325-meshis in volume percentages.

' Transverse 1 Iron, calcium silicide Graphite rupture, Resistivitystrength, ohm in' in volume percentages. J

The following compacts were fabricated from graphite powder and amixture of 15 percent magnesium ferro silicon and 85 percent ironpowder. The compositions given in the table below are in volumepercentages.

A further series of compacts were prepared containing 5.0 percentcalcium silicide and the following properties were obtained.

Metal volume, percent 10 2O 30 40 50 Transverse rupture strength p.s.i5, 500 14, 500 21, 000 28, 250 40, 000 Tensile strength, 6, 500 10, 90014, 800 10, 500 Compressive strength 11, 400 14, 400 25, 500 51, 300Elongation, percent. 0. 1.0 2. 0 Porosity, percent 21. 7 20. 8 22. 9 19.13. 8

The above compacts were sintered for one hour at a temperature of 2300F. in vacuum.

Cobalt graphite compacts were prepared from cobalt powder and graphitepowder which had been separately ground to pass a 325 mesh screen andthen ball milled together in benzene for four hours to insure propermixing. The mixture was cold pressed in a hardened steel die usingpressures of 50,000 to 100,000 pounds per square inch. The compacts weresintered in a vacuum of from 100 to 200 microns and in ambients ofhydrogen, helium and argon. The temperature of sintering was 2500 F. andthe time was sixty minutes.

The following compacts were fabricated from graphite powder and amixture consisting of 5 percent by weight calcium silicide and 95percent by weight cobalt powder. A cobalt powder of 325 mesh issuitable. The compositions given in the following table are in volumepercentages.

Transverse Cobalt, calcium silicide Graphite rupture Resistivitystrength, ohm in-- p.s.i.

The following compacts were fabricated from graphite powder and amixture consisting of 5 percent by weight barium silicide and 95 percentby Weight cobalt powder. The compositions given in the table below arein volume percentages.

The following compacts were fabricated from graphite powder and amixture of 15 percent magnesium ferro silicon and percent cobalt powder.The compositions given in the table below are in volume percentages.

g Transverse Cobalt, ierro silicon Graphite rupture Resistivitystrength, ohm in p.s.i.

Copper graphite compacts were prepared from copper powder and graphitepowder which had been separately ground to pass a 200 mesh screen andthen ball milled together in benzene for four hours to insure propermixing. The mixture was cold pressed in a hardened steel die usingpressures of 50,000 to 100,000 pounds per square inch. The compacts weresintered in a vacuum of from 100 to 200 microns and in ambient ofhydrogen, helium and argon. The temperature of sintering was 2000 F. andthe time was sixty minutes.

The following compacts were fabricated from graphite powder and amixture consisting of 5 percent by weight calcium silicide and percentby weight copper powder. A copper powder of 200 mesh is suitable. Thecompositions given in the table below are in volume percentages.

Transverse Copper, calcium silicide Graphite rupture Resistivitystrength, ohm inp.s.i.

barium silicide and 95 percent by weight copper powder.

The compositions given in the table below are in volume percentages.

Transverse Copper, barium silicide Graphite rupture Resistivitystrength, ohm inp.s.i.

The following compacts were fabricated from graphite powder and amixture of 15 percent magnesium ferro silicon and 85 percent copperpowder. The compositions given in the table below are in volumepercentages.

Transverse Copper, ferro silicon Graphite rupture Resistivity strength,ohm inp.s.i.

The following compacts were fabricated from graphite powder and amixture of 15 percent of copper magnesium and 85 percent copper powder.The compositions given in the following table are in volume percentages.

Transverse Copper, copper magnesium Graphite rupture Resistivitystrength, ohm inp.s.i.

Nickel graphite compacts were prepared from nickel powder and graphitepowder which had been separately ground to pass a 140 mesh screen andthen ball milled,

powder and a mixture consisting of 5 percent by weight calcium silicideand 95 percent by weight nickel powder. A nickel powder of 325 mesh issuitable. The compositions given in the table below are in volumepercentages.

Transverse Graphite rupture Resistivity Nickel, calcium silicidestrengith, ohm in The following compacts were fabricated from graphitepowder and a mixture consisting of 5 percent by weight barium silicideand 95 percent by weight nickel powder. The compositions given in thetable below are in volume percentages.

Transverse Nickel, barium silicide Graphite rupture Resistivitystrength, ohm inpsi.

The following compacts were fabricated from graphite powder and amixture of percent magnesium ferro silicon and 85 percent nickel powder.The compositions given in the table below are in volume percentages.

- Transverse Nickel, ferro silicon Graphite rupture Resistivitystrength, ohm inp.s.i.

- Transverse Nickel Magnesium Graphite rupture Resistivity r strength,ohm in- The following compacts were fabricated from graphite powder anda mixture consisting of 5 percent by weight calcium silicide and 95percent by weight silver powder. The compositions given in the tablebelow'are in volume percentages.

Transverse Silver, calcium silicide Graphite rupture Resistivitystrength, ohm inp.s.i.

6 The calcium silicide contained approximately 33' percent calcium. i

The following compacts were prepared from graphite powder and a mixtureconsisting of 5 percent by weight barium silicide and percent by weightsilver powder. The compositions given in the following table are involume percentages.

Resistivity Silver, barium silicide ohm in- Graphite The barium silicidecontained approximately 45 percent barium, remainder substantially allsilicon; 1

Three aluminum graphite compacts have been fabricated. They weredesignated 81-17, 81-27, and 81-28. The composition of these are asfollows:

Cu-3. 57 Mg-l. 46 Ni-2. 04

Zn3. 02 Al-89. 725

Fe(). 10 A.l86. 12

They were filed down by hand into powders to pass through a mesh screen.

They were then mixed withzthe Acheson graphite 38 powder in 50-50 byvolume proportions.

These were pressed in a hardened steel die and sintered in vacuum at1800 F.

' No sweating was observed.

Compacts of equal parts by volume of a minus 325 mesh diamond powder anda mixture of 10 percent by weight of calcium silicide powder and 90percent by weight of copper powder were formed by pressing the pre-mixedpowders in a hardened steel die at a pressure of 100,000 p.s.i. Thesecompacts were sintered in an argon atmosphere to a temperature of 2020F. A sound,

hard sintered compact resulted with all the metallic phase beingretained in the compact.

Similar results were obtained with compacts formed by pressing at100,000 p.s.i., containing equal parts by volume of a minus 325 meshdiamond powder. and a mixture composed of 10 percent by weight ofcalcium silicide powder and 90 percent by weight of silver powder. Thesecompacts were sintered in an argon atmosphere at 1850 F.

We claim:

1. A sintered metal bonded composition containing as essentialingredients a substance selected from the group of substances consistingof graphite and diamond and between ten and seventy percent by volumemetal selected from the group of metals consisting of iron, cobalt,nickel, copper, silver and aluminum, and a small but effective additionof at least one metal selected from the group of metals consisting ofcalcium, magnesium, barium and strontium, said addition being present inan amount sufficient to substantially prevent the metal content of thecomposition from sweating out during the sintering operation.

2. A sintered metal bonded graphite composition containing as essentialingredients graphite and between ten and seventy percent by volume metalselected from the group of metals consisting of iron, cobalt, nickel,copper, silver and aluminum, and a small but effective addition of atleast one metal selected from the group of metals consisting of calcium,magn'esium,.barium and strontium, said addition being present in anamount sufficient to substantially prevent the metal content of thecomposition from sweating out during the sintering operation.

3. A sintered metal bonded diamond composition containing as essentialingredients diamond and between ten and seventy percent by volume metalselected from the group of metals consisting of iron, cobalt, nickel,copper, silver and aluminum, and a small but eflective addition of atleast one metal selected from tne group of metals consisting of calcium,magnesium, barium and strontium, said addition being present in anamount suiiicient to substantially prevent the metal content of thecomposition from sweating out during the sintering operation.

4. A sintered metal bonded graphite composition containing as essentialingredients graphite and between ten and seventy percent by volume iron,and a small but effective addition of at least one metal selected fromthe group of metals consisting of calcium, magnesium, barium andstrontium, said addition being present in an amount sufiicient tosubstantially prevent the metal content of the composition from sweatingout during the sintering operation.

5. A sintered metal bonded graphite composition containing as essentialingredients graphite and between ten and seventy percent by volumecobalt, and a small but eitective addition of at least one metalselected from the group of metals consisting of calcium, magnesium,barium and strontium, said addition being present in an amountsuificient to substantially prevent the metal content of the compositionfrom sweating out during the sintering operation.

6. A sintered metal bonded graphite composition containing as essentialingredients graphite and between ten and seventy percent by volumenickel, and a small but effective addition of at least one metalselected from the group of metals consisting of calcium, magnesium,barium and strontium, said addition being present in an amountsufficient to substantially prevent the metal content of the compositionfrom sweating out during the sintering operation.

7. A sintered metal bonded graphite composition containing as essentialingredients graphite and between ten and seventy percent by volumecopper, and a small but effective addition of 'at least one metalselected from the group of metals consisting of calcium, magnesium,barium and strontium, said addition being present in an amountsufiicient to substantially prevent the metal content of the compositionfrom sweating out during the sintering operation.

8. A sintered metal bonded graphite composition containing as essentialingredients graphite and between ten and seventy percent by volumealuminum, and a small but effective addition of at least one metalselected from the group of metals consisting of calcium, magnesium,barium and strontium, said addition being present in an amountsufiicient to substantially prevent the metal content of the compositionfrom sweating out during the sintering operation.

9. A sintered metal bonded diamond composition containing as essentialingredients diamond and between ten .and seventy percent by volume iron,and a small but effective addition of at least one metal selected fromthe efifective addition of at least one metal selected from the group ofmetals consisting of calcium, magnesium, barium and strontium, saidaddition being present in an amount suflicient to substantially preventthe metal content of the composition from sweating out during thesintering operation.

11. A sintered metal bonded diamond composition containing as essentialingredients diamond and between ten and seventy percent by volumenickel, and a small but effective addition of at least one metalselected from the group of metals consisting of calcium, magnesium,barium and strontium, said addition being present in an amountsufficient to substantially prevent the metal content of the compositionfrom sweating out during the sintering operation.

12. A sintered metal bonded diamond composition containing as essentialingredients diamond and between ten and seventy percent by volumecopper, and a small but effective addition of at least one metalselected from the group of metals consisting of calcium, magnesium,barium and strontium, said addition being present in an amountsufficient to substantially prevent the metal content of the compositionfrom sweating out during the sintering operation.

, 13. A sintered metal bonded diamond composition containing asessential ingredients diamond and between ten and seventy percent byvolume aluminum, and a small but effective addition of at least onemetal selected from the group of metals consisting of calcium,magnesium, barium and strontium, said addition being present in anamount sufiicient to substantially prevent the metal content of thecomposition from sweating out during the sintering operation.

14. A sintered metal bonded graphite composition containing as essentialingredients graphite and between ten and seventy percent by volume iron,and a small but eliective addition of calcium, said addition beingpresent in an amount sufficient to substantially prevent the metalcontent of the composition from sweating out during the sinteringoperation.

References Cited in the file of this patent UNITED STATES PATENTS1,053,880 Scott et a1 Feb. 18, 1913 1,636,763 Boring July 26, 19271,775,358 Smith Sept. 9, 1930 2,191,936 Lenel Feb. 27, 1946 2,416,830Heuberger Mar. 4, 1947 FOREIGN PATENTS 172,693 Great Britain Dec. 1,1921 465,936 Great Britain May 13, 1937

1. A SINTERED METAL BONDED COMPOSITION CONTAINING AS ESSENTIAL INGREDIENTS A SUBSTANCE SELECTED FROM THE GROUP OF SUBSTANCES CONSISTING OF GRAPHITE AND DIAMOND AND BETWEEN TEN AND SEVENTY PERCENT BY VOLUME METAL SELECTED FROM THE GROUP OF METALS CONSISTING OF IRON, COBALT, NICKEL, COPPER, SILVER AND ALUMINUM, AND A SMALL BUT EFFECTIVE ADDITION OF AT LEAST ONE METAL SELECTED FROM THE 